How is material dependent damping (MP,DAMP) used in a psd analysis?


In a spectrum analysis, material dependent damping is treated as a ratio to critical for
each material. Note that the damping must be specified in the modal and element results
must be expanded.

Here is a test which shows how small values of damping change the psd results.
The psd response does vary inversely when damping is changed from .01 to .005.

/prep7
/title,Role of MP,DAMP in a PSD analysis
et,1,63
r,1,.1
mp,ex,1,28e6
mp,dens,1,0.0007

mp,damp,1,.005 ! material dependent damping

rect,,10,,1
esize,1
amesh,1
nsel,s,loc,x,0
d,all,all
nsel,all
fini

/solu
antype,modal,
modopt,lanb,1
mxpand,1,,,yes
solve
fini

/solu
antype,spectrum
spopt,psd,10,on
psduni,1,accg
psdfrq,1,,10,100,1000,1100
psdval,1,.6,.7,1,.1
psdres,disp,abs
psdres,acel,abs
nsel,s,loc,x,0
d,all,uz,1
nsel,all
outpr,nsol,1
pfact,1,base
psdcom
solve
fini
/post1
set,list
set,3,1

prns,u





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